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Figure 1.
Figure 1. Overall structure of the hTcf4-CBD -  -catenin
armadillo repeat complex. a, Two views of the  -catenin
-hTcf4-CBD complex, rotated about the superhelical axis of -catenin
by 180°. The -catenin
armadillo repeat region is made up of 12 repeats, each
consisting of three helices, except for repeat 7, which is made
up of only the second and third helices. The three helices for
each repeat are denoted in blue, green and yellow, with the
yellow helices forming the platform upon which the hTcf4-CBD
(red) sits. The hTcf4-CBD lies along the platform of -catenin
in an antiparallel fashion with respect to the N- and C-termini
of -catenin.
The hTcf4 structure presented here consists of three discrete
modules (from the N-terminus to the C-terminus): a -strand,
a region that contains the kinked  -helix
and another extended segment followed by the C-terminal -helix.
The N-terminus of the hTcf4 in this structure is disordered, as
denoted by dashed lines. This figure was generated by
MOLSCRIPT25 and RASTER3D^26. b, Sequence alignment of hTcf4-CBD
and the XTcf3-CBD, with the structure of each Tcf shown in red.
Three critical contacts have been colored, with two of these
(turquoise) conserved in the hTcf4-CBD and XTcf3-CBD structure:
Asp 16, which binds the first charged button of -catenin,
and Leu 48. The third contact occurs between the second charged
button of -catenin
and a Glu in a conserved acidic cluster of Tcf family members.
The Glu in the structure reported here and that reported for the
XTcf3-CBD^15 is yellow, and the other Glu residues are green.
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